Production of ammonia and catalytic agents for use therein.



UNITED sTATns PATENT OFFICE.

, CARL Boson, ALWIN MIfrrAscH, nun nuns WOLF, or LUDWIIGSHAFEN-ON-THE- mama, AuncEoRe suntan, or MANNHEIM, GERMANY, nssreuons T0 BADISCHE' ANILIN & SODA FABRIK, OF LUDWIGSHAFEN-ONfTHE-RHINE, GERMANY, A CORPO- VRATION.

No Drawing. Original application filed December 24, 1910, Serial N 0. 599,100.

Specification of Letters Patent.

PRODUCTION OFAMlMONIA AND CATALYTIC AGENTS FOR USE THEREIN.

' Patented July 29, 1913. Divided and this application filed January 10, 1912. Serial No. 670,445.

To ZZZZ whom it may concern Be it known that we, CARL Boson, ALWIN Mrrrason, HANs WOLF, and Gnono STERN, subjects the first andfourth of the King of Prussia, the second of the King of Saxony, and the third-of the Kingv of Bavaria, residing the first three at Ludwigshafen-on-the- Rhine and the fourth at Mannheim, all in Germany, have invented certain new and useful Improvements in the Production of Ammonia and Catalytic Agents for Use Therein, which invention is divided out of our application for Letters Patent filed .December 24, 1910, Serial No. 599,100, and of which the following is a specification.

Our invention relates to the manufacture of ammonia bysynthesis from its elements and in catalytic agents for use in the said manufacture.

In the-specification of our application for patent Serial No. 599,101 we have described a new form of iron which is capable of use as a catalytic agent in the-manufacture of ammonia from its elements, and we have further shown that the catalytic power of iron can. be improved by the presenceof certain bodies which we have termed pro- We have further shown in the said specification that certain other bodies act as contact poisons and tend to destroy the catalytic power of iron for converting a mixture of nitrogen and'hydrogen into ammonia. Further, in the application for patent Serial No. 599,100 is described and claimed generically the production of ammonia when making use of a catalytic agent, together with a promoter in each case. In this present application .we now desire to claim specifically-the production of ammo nia while making use of cerium and a promoter, and also such catalytic mixture itself.

Such production and catalytic mixture are claimed generically in the aforesaid applicationfor patent serial No. 599,100, but are not claimed specifically therein. In continuing our researches-on the synthetic manufacture ofammonia from its elements, we have further discovered that. the power of cerium as a catalytic agent for theproduction of ammonia by synthesis can also be improved by the presence of promoters, and that other bodies act as contact poisons. As a general rule admitting of several exceptions, compounds of the alkali metals and the alkaline earth metals act as promoters of the -c talytlc power. On the other hand, the m at loids, such for instance as sulfur, selenium, tellurium, arsenic, phosphorus, andalso the easily fusible and easily reducible such for instance as lead, tin, and Zinc 11- orally act as cont-act poisons, whether the said element be added or be present. as such or in the form of a suitable compound thereof, Since it is evident that during the passage of the mixture of hydrogen and nitrogen over the contact material the body or promoter added may undergo some chemical change, We do not wish to be understood as confining our invention to the use of the specific compounds of the elements mentioned.

Although we have mentioned a number of bodies which act as promoters and a num ber of instances of contact'poisons, these in stances do not exhaust the number of bodies having the efl'ects mentioned. 'We have found that an enormous number of bodies have more or less action in the Ways mentioned, and these bodies belong to various classes of chemical substances, so that it is impossible .to give a definition of promoters in terms, making the class of promoters coincidentwith some class or classes of chemical bodies. Thus we have found that bodies that are not alkaline earths or alkaline metals or compounds thereof will act as promoters, and we do not desire our patent to be restricted to promoters which fall into the classes of alkaline earths and alkalis. have devised a simple test whereby it can readily be ascertained whether any body is a promoter in the sense of this specification. The test is conducted as follows: Prepare an intimate mixture of the test body and the cerium catalyst in a suitable way. This may be done in some cases by mechanical mixture, in others by chemical precipitation 'on the catalyst, or by mixing amalgams .of the two met-als and then distilling 01f the mercury, or by a suitable combination of one or more of these methods. Set the product so obtained as a catalyst in a tube-furnace side by side with another tube containing an equal quantity of the untreated catalVe lyst without any addition, and pass equal currents of a mixture of nitrogen and hydrogen in their combining proportions through both tubes under identical conditions, and measure the quantity of ammonia obtained in both cases. If the yield of ammo-nia be increased by the treatment with the added body, this may be regarded as a promoter.

As instances of the bodies which can be employed as promoters according to our invention, we mention oxids or other suitable compounds of the group of alkali metals, or the alkaline earth metals, of the group of easily be obtained.

' The following example will serve to illustrate further the nature of our invention, which, however, is not in any way confined to this example: Take metallic cerium which has been prepared electrolytically and is in the condition of small grains, and mix it with about two per cent. of its-weight of powdered potassium nitrate, and then place the mixture in the contact tube. On passing a mixture of nitrogen and hydrogen which is completely dry and free from oxygen and contact poison through the tube, while heating, a catalytic agent is obtained which gives about three times the yield of ammonia which the untreated cerium gives. Ammonia can for instance be obtained by passing pure hydrogen and nitrogen in combining proportions over the catalytic agent at about 550 C. and at a pressure of 150 atmospheres.

It has been found advantageous that the catalytic mixture consist of cerium and a promoter which belongs preferably to a different group or, at any rate, to a different sub-group of the periodic system. Thus, for

instance, mixtures of cerium and magne sium, or of cerium and molybdenum, are also suitable for the purposes of this invention.

We do not claim in this present application generically the productionof ammonia while makingiuse of a catalytic agent together with a promoter in each case, such production and such catalytic mixtures being embodied in the claims of the aforesaid application for patent Serial No. 599,100, filed December 24, 1910.

Now what We claim is 1. An active catalyst for the manufacture of ammonia from its elements containing cerium and a promoter. l

2. An active catalyst for the manufacture of ammonia from its elements containing cerium and an. oxid of an alkali-forming metal.

3. An active catalyst for the manufacture of ammonia from its elements containing cerium and potassium oxid. 4. The process of manufacturing ammonia by passing a mixture containing nitrogen and hydrogen free from contact poison over an active catalyst containing cerium and a promoter. i

5. The process of manufacturing ammonia by passing a mixture containing nitrogen and hydrogen free from contact poison over an actlve catalyst containing cerlum and an oxid of an alkali-forming metal.

6. The process of manufacturing ammonia by passing a mixture containing nitrogen and hydrogen free from contact poison over an active catalyst containing cerium and potassium oxid.

In testimony whereof we have hereunto set our hands in the presence of two subscribing witnesses.

Witnesses:

J. Auto. LLOYD, A. O. TITTMANN. 

